Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already establish the safe-read profile (readOnlyHint, idempotentHint, destructiveHint=false), so the bar is lower, and the description still adds substantive behavior: chronological ordering, the presence of is_forwarded/forward_origin fields, and the semantic distinction that 'from' on a forward is the forwarder, not the original author. The explicit warning against inferring a hidden author's identity is genuinely useful anti-hallucination context beyond any structured field.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loaded with the core purpose and ordering, then the prerequisite, then the forward-handling caveats. The trailing sentences about authorship are longer than typical but each prevents a concrete misinterpretation of returned data, so they earn their space. No redundant restatement of the name.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With no output schema, the description carries the burden of explaining the returned message shape, and it does so for the tricky parts (is_forwarded, forward_origin, from semantics). For a 4-parameter read tool this is nearly complete; the main omission is explicit paging behavior for 'before', though the schema covers that parameter's meaning.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so limit/since/before/chat_id are already fully documented in the schema and the baseline is 3. The description only adds that chat_id comes from telegram_find_chat and that results are oldest-first; it does not clarify the since/before paging semantics beyond what the schema states.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource ('Message history of one conversation') plus the ordering ('oldest first so it reads as a transcript'). It routes to telegram_find_chat for chat_id, but never differentiates itself from the close siblings telegram_recent_messages and telegram_search_messages, which also return messages. Clear purpose, incomplete sibling discrimination.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Gives one actionable prerequisite ('Resolve a person's name to chat_id with telegram_find_chat first') and a caution about interpreting forwards. However, it offers no guidance on when to choose this over telegram_recent_messages or telegram_search_messages, so the when-to-use decision for a full-history read vs. a recent/search read is left implicit.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.